When a marijuana plant is in a mature enough state where the top of the plant is knee high. This is based off of a 5 ft 10" human structure.
Hey man, did you hear that Filmer got High Knees for sale?
by The Gig Harbor Lingo March 09, 2010
The backside of a person that is placed in a chair.
If you do that it will come back to bite you in the highknee.
by BSC Young Boiis May 01, 2011